1. Technical Field of the Invention
This invention relates to instrumentation for monitoring of motion and flexure of body joints and digits. In particular, it relates to flexible film based sensor configurations for monitoring body joint movement, suitable for use with body-mounted appliances and specialized signal processors with discrete audible or colored light and other biofeedback capabilities.
2. Discussion of Prior Art
The art of user figment with medical devices for injury avoidance and rehabilitation therapy is not new. However, as with medical care and treatment in general, it used to be conducted with a somewhat cavalier attitude about cost. The xe2x80x98if it doesn""t cost a lot in can""t be any goodxe2x80x99 attitude, was driven home to the applicant some years ago when a new state of the art oscillometer product costing a conservative (US)$300 was offered to a surgeon who quipped, xe2x80x9cI paid that for the light I wear in the operating room,xe2x80x9d and declined to consider it further.
Now, however, we have entered an era of greater emphasis on reduction and control of medical care and treatment costs. There is a new willingness by the medical care delivery establishment to consider and even search for lower cost products that offer bonafide medical benefits. The need for lower cost medical products extends to injury prevention and rehabilitation devices.
There are, in the prior art, body suit implementations for general measurement of body activities for injury avoidance training and/or physical rehabilitation. One body suit, disclosed in U.S. Pat. No. 4,729,377, requires points of electrode contact with the skin and requires soaking the garment with conductive fluid to select the measurement points of interest. Another suit, disclosed in U.S. Pat. No. 5,375,610, encompasses the entire body and measures inclination by a plurality of mercury switches. Both are costly examples of accomplishing generalized monitoring at the expense of ease of use, and do not lend themselves to casual use as in sports training or for prolonged use in repetitive or continuous motion. These types of devices are more appropriate for specific data collection testing sessions rather than for everyday wearing to monitor body motion for injury prevention or rehabilitation in the industrial setting.
Many prior art devices utilize standard transducer technology that is rigid and has low electrical sensitivity. The former creates a comfort issue when integrated with a user system while the latter generates a need for electrical shielding and high gain amplification, limiting both cost and function.
In addition to the medical need, professional and recreational training activities for kinetic sports share the requirement for low cost, effective monitoring of body motion. Common problems facing both industries are the need for a system or inventory of low cost associated devices to meet the needs of athletes and patients of different sizes; the need for a flexible scheme for universal figments adaptable to each part of the body; the need for a self-monitoring system and methodology that is easy for the athlete or patient to remove and reinstall daily, and to use and interpret so as to realize the full benefit.
More specifically, industry data clearly indicates a large amount of pain, suffering, lost time and lost productivity results from back injuries that occur on and off the job from lack of training or improper training and monitoring in lifting and related activities. Lifting is a general problem, while twisting while lifting or repetitive twisting such as when moving parts along a production line are also statistically very significant contributors to employee injuries.
One example of a recently introduced commercial body motion monitoring device is the Spine Tuner(trademark) by Clear Sky Products, a posture monitor consisting of a belt that goes around the back approximately half way between the waist and shoulder that holds a small system module against the spine. The system module consists of a pressure-activated switch that is actuated by pressure, forcing the housing to compress front to back, actuating the switch. When the switch is closed, a battery is connected directly to a small motor with unbalanced weight, to cause vibrations that are noticeable to the user. Adjusting the contact spacing on a stamped metal switch by turning an adjustment screw sets the system sensitivity. This operation cannot be performed while the device is being worn, which requires the user to use an awkward trial and error approach to obtain a useful setting. The feedback scheme for the Clear Sky device utilizes a single threshold at which a signal is initiated.
An example of the need for body motion monitoring in the sports training category is the game of golf. The new buzzword in the golf industry for the past five years or so is the xe2x80x9cXxe2x80x9d factor, a rotation of the shoulders relative to the hips. The need to monitor spinal twisting in this instance is similar to some industrial requirements.
It is common for workers in some companies and industries to be required to wear back support belts. Home Depot and the Marriott Chain are among companies believed to require the use these devices for employees in lift-related jobs. Interviews with workers that are required to wear these belts have produced comments such as, xe2x80x9cNow that I have support I can lift heavier thingsxe2x80x9d, which defeats the primary purpose; and xe2x80x9cI have to wear it but I don""t think it does anything.xe2x80x9d There seems to be an acceptance and confidence problem with these commonly required devices that defeats or reduces their intended benefit.
Much of the technology for medical and sports requirements rely on braces. A sport brace called The Secret(trademark), endorsed by golf pro Greg Norman, sells at a premium price, but constrains the user to a particular position of the wrist, an approach that is not likely to promote good muscle memory.
Braces in general have a number of problems, they are uncomfortable, frequently they do not quite fit the subject or the need, in training they do not promote good muscle memory, they can cause injury by constraining too well during a required activity, particularly in athletics, and they can promote xe2x80x9cfalsexe2x80x9d confidence causing users to try to over perform. When these devices are removed, everyday performance seems awkward.
What is needed, for both medical and athletic fields, is a low cost system and methodology of devices, sensors and biofeedback mechanisms that are flexible and adaptable to various body motions, comfortable to wear, and easy to understand and use.
Our research, as disclosed in this and previously filed applications, shows that discrete, multi-level thresholds of realtime biofeedback, where the feedback mechanism holds the peak a value of the measured parameter sufficiently long or otherwise emphasizes it to ensure user awareness, enables more meaningful comprehension of the relationship between the effort and the motion response. A limited set of frequency-discrete tones of audio feedback, or of color discrete light feedback, accomplish this end.
Not all means of sensory awareness are suitable for this more complex type of biofeedback. Vibration, for example, as with a mechanical device worn where its physical vibrations are noticeable to the wearer, is known to be viable for single threshold, on/off type signals. However, most users"" level of sensitivity to this type of messaging is too low to discriminate between even a limited set of different vibration frequencies or amplitudes, particularly in a realtime environment. Physically displaced points of vibration may be suitable for messages with significantly different meaning, but may be too distracting for usefully tracking the acceleration common to repetitive human movements.
A non-invasive monitoring system with discrete audible or lighted color, used on a repetitive basis, makes it clear that the user is approaching a danger limit, eliminating the over confidence factor and encouraging compliance with proper lifting or other pertinent motion technique, and ultimately teaching the user what effort will generate the best result.
A biofeedback system with unique sensors is herein disclosed that allows for a universal monitoring methodology to be applied to the physical therapy needs for the human body. The system combines configurable mounting appliances, compatible motion sensors, coded means for positioning and orienting sensors at any location of the body, with a small, self-contained signal processing and feedback module. Multi-level instant audible feedback, or multi-level visual feedback such as by a set of different colored LED""s or other visual display of discrete colors, is employed to provide a quick learning environment. Motions of the back, torso, limb joints and digits relevant to the general task of concern, can be selected and monitored by the sensors of the invention. Specific embodiments employing the concepts and methodology focus on the back of limb joints, i.e. the elbow, wrist, digits, knee and ankle. Other embodiments are taylored towards proper lifting motion, and on avoiding twisting of the back while lifting or performing common repetitive industrial movements that have a proven history of harming the performer.
Several embodiments of a low force, high compliance, long extension, body motion sensor are disclosed, which strengthen the monitor system concepts,. These enhance the functionality, simplicity and cost of the resulting system implementation. The invention employs compliant, large area, low cost, flexible piezofilm as the core element of a flexure sensor, attached to any of several different somewhat less flexible or semi-flexible, backbone members of somewhat larger surface area. In some cases, the flexible piezofilm sensor being attached to the less flexible backbone acts to integrate localized strain anomalies and produce an average signal voltage of the flexure to which the combination is exposed. This combination preserves the xe2x80x9csoft comfortablexe2x80x9d requirement aimed at achieving user compliance, while employing low cost, easy-to-fabricate, sensor methodology.
The sensors of the invention enable a universal body motion biofeedback kit capable of providing the doctor or therapist with an in-office components package from which a suitable biofeedback system can be configured, fitted and adjusted; for a range of different patients, and for a range of different patient problems. The customized system is what the patient wears out of the office. Development of the soft flexible force and motion transducers disclosed herein, were necessary to optimize the universality of the components package or biofeedback kit in the hands of the doctor or physical therapist, to meet all of the objectives of the invention.
Further, it is possible to provide a system for volume application such as for works at Home Depot(trademark), the Marriott(trademark) chain, and the like, or for supermarket employees. These systems would be factory set to baseline statistics for harmful moves or conditions providing warning over a wide range of conditions of the measured variable or variables. These would not need the assistance of a doctor, therapist or trainer. They could be fitted with a fine adjustment control to account for differences in individuals, settings that could be described using base line movements to allow the user to arrive at the proper threshold indication for that reference move.
It was an object of a parent application to provide a mounting appliance system that allows motion sensors to be placed anywhere on the body with a chosen orientation and that is comfortable to wear and non-confining. Many of the athletic training devices on the market are uncomfortable constraining braces that force the user to a particular per-determined move that may not be correct for every user. The aforesaid mounting appliance system and the transducers and sensors disclosed herein are intended to be companion devices, although either may be used independently with other compatible devices.
An object of this invention is to provide a sensor system that allows abuser to isolate a single folding or twisting motion of the body with a suitable sensor/appliance combination, (e.g. flexing the wrist in a particular plane), so as to provide sensing and instant feedback to cue for proper motion performance and warn against improper motions. It is a related objective to promote a training methodology for such motions, including a xe2x80x9cone thing at a timexe2x80x9d focus and a natural learning by doing process.
The transducer concepts disclosed herein meet these needs. There are four general transducer configurations within the scope of the invention, all sharing a common dependence on a flexible film sensing element: oval, half oval, trident and compression pad. The oval and half oval lend themselves to mounting in elastic bands such as suspenders, the trident lends itself to mounting at a joint in a wrist, elbow or knee, while the compression pad is optimum for application along the spine. Additionally, introduction of a static overlay switch greatly enhances system capability by introducing one or more absolute levels for the parameter being measured, such as minimum, maximum or optimal, to the sensors of the invention.
An object of this invention is to include in the training system, capability for adjusting the system sensitivity to accommodate different levels of skill, performance, application or severity, in a manner that is simple to set up and adjustment. Many existing training systems for athletic activities compare and force the user to accept a pre-determined average motion or range of motion. The transducers disclosed herein have linear output and the range required for optimum parameter adjustability and threshold selection with a suitable control module.
An object of this invention is to provide a limb/body sensing and monitoring system that enables very low cost implementation. Medical systems that help a patient with recovery and rehabilitation, historically, have been expensive and frequently require fitting and ordering of a custom device. The disclosed invention provides a means for in-office configuration and setup of the system so that the patient can leave with a properly fitted custom aid or biofeedback system, and where the fitting xe2x80x9cbreadboardxe2x80x9d and the final device are one and the same, promoting lower costs and reduction in stock requirements.
An object of this invention is to provide training systems easy to wash, clean, or sterilize. These transducers, a preferred example using a Kynar(trademark) flexible piezofilm sensor, are inert to a range of solvents. For example, a common use of Kynar(trademark) film is to line caustic tanks to avoid corrosion. These transducers can be plated, or alternatively deposited with inert elements such as gold, for electroding the transducer film, to preserve environmental inertness.
Further objects and advantages of this invention will become apparent from a consideration of the drawings and ensuing description.